2 class C network

[Greg Chu <gchu () delnet net>]

Hi,
I need help to sniffer two class C network

network 1 connect to network 2 through a cisco router
my servers are on network 1.  my network 2 connect to around 150 users.
if I put snort on one of the server on network 1, then I only see traffic 
logged on network 1.

My question is how can I see traffice on network 2 which is interfaced 
through the router.

all traffice to network 2 is routed to the ip of the ethernet 0 on the 
router.

Or I have to put snort on network 2 to see the traffic.

When I install snort on 1 pc on network 2, which is a xp machine, it says 
wincap can not find host name.

Any help is appreciated.

Thanks!
Greg